I have a former working background in surveying calcs and mapping, and have also been long considering embarking upon a similar DIY project for my own property.
One aspect I note, having spent quite some time at it myself, is that there is somewhat of an art to the generation of accurate topographical contour lines from a set of manually surveyed points. Both in what points to survey, and in how to treat the points. The reference term here is TIN or Triangulated Irregular Network. Automated software does a fair job of building TINs, but the resulting contour lines can in some areas represent detail or features that don't really exist.
For example in the author's contour maps under the "Finally, The Mapping" section, much of the leftmost half is particularly sparse in measured points and as a result, the contour lines have interpolated some wacky humps-and-hollows across that half of the land, at least some of which probably don't exist in reality. (Technically speaking, long skinny triangles = not ideal, particularly at large scale; and separately, another key word or concept to look into is that of topographical "breaklines")
Ultimately, the specific arrangement of triangles in the TIN defines how the contour lines will be drawn. Good starting data is half the equation, and the other half is how you TIN it.
You're correct, my data is still too sparse in some areas to give a good set of contours. It's been fun to see how the contours change as I add more data to the survey. It's part of the reason I decided to buy my own gear, because then I can spend as much time collecting data as I want without more cost.
https://forums.overclockers.com.au/threads/calling-all-sketc...
Quite outdated now in many respects - and using work software worth thousands, at the time! (modern QGIS is great) - but you might find some of the crossover detail interesting.
https://webcache.googleusercontent.com/search?q=cache%3Ahttp...
Great writeup, may add to my list of projects for 2024.
In my high school in 1980, we took a 2-hour survey/questionnaire filling in circles with a #2 pencil, and we we waited 3 to 4 weeks to get the results of what career we were suited for, and mine was cartographer! I imagine there were humans and machines doing the analysis back then, but maybe I should have followed that path!
I was once going through the same process and considered buying from them. But then a more official survey turned out to be rather cheap so I did not have any need any more.
What are the laws in that place? Could you, let's say, not do any surveying, build a fence, and then have a new neighbour show up 25 years later with a survey and ask you to move it?
Here, we have this law that if you occupy some piece of land for 20 years (with no "malice", if it can be proved you knew it wasn't your land the amount of time is 30 years). After that time it essentially "becomes yours". The neighbour had no fence, but I imagine he could argue his camper being there for the required amount of time fulfills the requirement and then I imagine the boundary would get redrawn.
What is the authoritative thing that defines the boundary in absence of pins/markers?
The authoritative thing is the boundary descriptions for your purchase (See my comment https://news.ycombinator.com/item?id=38829732 for what that looks like)
first, absolutely fascinating topic, and solid write up. i skimmed through certain bits but am wondering: "Turns out, the survey was off a lot more than any of us expected" did you mean off from the title, or the surveyor's work? (also, since you're in Canada, allow me to quote Les Stroud: "if you sweat, then you die" sweating is actually the easiest way to get cold heh, you brought sweat up in the same paragraph)
second, i'm a musician who lives in Anchorage. i'm a recovering programmer. a good friend of mine is a recovering surveyor, and he runs Trapper Creek music festival up here, 15 years and counting. since you said you mounted equipment on a mic stand you just happened to have -- wondering if that event you were planning for was music related :-D
The data from GeoNB was way off from what the surveyor properly located.
> wondering if that event you were planning for was music related
There may be a band, but I just happened to have an old mic stand handy for that temporary test :D
Do you have more posts about how you went about buying the land?
The surveying aspect is super interesting, including the fact that your neighbor had such an imprecise knowledge of their boundaries.
I wonder what the history of surveying looks like... I assume as mapping precision increased there must have been many many cases where structures were found to lie on neighboring properties.
And I assume now property boundaries are kind of based on a mixture of all of this? But there's a trend toward WGS84 coordinates or similar?
I also assume along the way measurement mistakes have been reasonably common or situations where those "stable" features in the landscape turned out to be not so stable.
Resolving all these issues must be a nightmare and while I've been vaguely aware of this history of surveying it now seems like it must be quite fascinating and I should try and read more about it.
https://www.kaggle.com/competitions/smartphone-decimeter-202...
https://www.euspa.europa.eu/european-space/galileo/services/...
https://barbeau.medium.com/gnss-interrupted-the-hidden-andro...
Also, you only get ~3cm precision while you have direct line of sight to a reasonable number of satellites, including some that are closer to the horizon. So if you're close to a building, or in a car with a metal roof - the accuracy might not turn out that great anyway.
People doing fancy surveys use a special antenna that rejects reflections from near ground level, but has to be pointed towards the sky. That's undesirable for a phone, where the user might want it in portrait or landscape, might hold it at an angle for readability, and so on. I have no idea if you could achieve respectable RTK performance with an omnidirectional antenna.
So even if you were the iPhone GPS chip selector, and you had the market leverage to get RTK support cheaply and get a killer deal on network NTRIP corrections, you might think the benefits aren't worth it.
I suspect costs will fall precipitously in the next few decades, though, because this sort of tech is useful for self-driving cars, and automotive order volumes tend to make chip prices fall a great deal.
OTOH at least in Europe there’s the EUPOS project that, if opened to the public, could very well provide good-enough corrections to give everybody high quality results.
The 0 cost solution would be to use this lidar data for topography, perhaps even for tree clusters, then use an aerial photo to help plot on some extras like roads. Maybe there's a little accuracy difference I'm not sure
[0] https://open.canada.ca/data/en/dataset/80ccc975-d6ec-9e24-a7...
Also, the accuracy, I expect that since I can get precise measurements, my maps of the streams, marshy areas, and other features are going to be a lot more comprehensive. Basically, I can get detail down to the level I want, just for the time I want to spend putting stick to ground.
In my game (geophysics) LiDAR is basically known for its ability to see through canopies -- through the virtual holes between leaves. They define the last arrival as "ground" level, and call it a day.
Now, I agree that deadfall (i.e. tree bits-and-pieces on the ground) has an ambiguity such that the tops of the deadfall would be reported as "ground" in the LiDAR definition. So, I expect that any residual map you might be able to create would -- in essence -- show the deadfall "topography".
Very nice project!!!
I actually prefer PPK over RTK for all work these days. RTK still gets used, but only to help control the drone's flight path in specific scenarios. Otherwise, uncorrected flight paths are fine since all the collected data is run through PPK after collection.
Since my goal isn't just getting terrain, but also mapping features in detail (I'm doing site planning for an event as well), I may as well skip the drone LIDAR because I'm going to be walking the ground anyway and I can do better than it can, was my conclusion.
FWIW, We use a LIDAR with co-aligned 20MP camera to get RGB point clouds and they are great for large space explorations.
